The Rockefeller University, through the Starr Center for Human Genetics, has created a Core facility for high throughput genotyping. This facility will be utilized by the Program Project group to develop mouse microsatellite mapping for the generation of speed congenics between the various transgenic and knockout strains generated by the Program Project. Since the infrastructure and instrumentation, described below, is already in place, the Program Project will contribute reagent costs ($0.25/genotype) and a full-time technician for DNA preparation, data assembly and overall responsibility for working with the Genotyping Core facility. Dr. Jeffrey Ravetch, the Program Project Director, will be responsible for overseeing the interactions of the Program Project team and the Genotyping Core.